Thread: Fuel vent

Tweet

Garage smells like raw gas had to park car outside, it is a 68 chevelle ss and builder put a big electric fuel pump in the back on frame rail and used 1 of the vent holes for a return fuel line and there is another one there and it is plugged off.,but don't car need to vent and is there anything I can do about the raw gas smells , and were are they coming from . I'm don't no what to do .smells all house up like gas wife not happy

You might have to add a charcoal canister and a vent if it does not have one now. My 40 only had a vented gas cap so any fumes/overflow came out of the fill tube down the side of the fender. Not ideal at all.

I make my own charcoal cannisters out of billet aluminum, however on a VW I made one really simple and easy out of PVC pipe, I used 2" PVC with a glued on cap on 1 end, tapped for a screw in hose barb on 1 end, the other end I fastened on and I drilled a series of 1/8" holes. I then took a (nylon pantyhose swiped from the wife) and then went to the aquarium supplies at the local Walmart and bought activated charcoal and filled the panty hose, tied it in a knot and slid it in the pvc tube, capped it attached the vent hose from the tank (make a loop in it higher than the tank) and you will never smell gas again, cost about 5-10 bucks unless its billet. Best of Luck Matt

IMO the charcoal canister is only to deal with fumes from the tank, and the only time you're going to get any venting from the tank is with a significant change in ambient temperature, like maybe having the car outside in the cold, taking it to the gas station and topping off the tank and then moving it into a warm garage where the fuel expands and vaporizes a bit. Most of the garage fumes problems are leaks, like the residual fuel pressure in the fuel rails passing leaky injectors, a blown diaphragm in a fuel pressure regulator, fuel boiling out of the carb bowls, etc.

I wouldn't start chasing finding/making a charcoal canister until you know that it's just tank fumes. Use your nose to hunt for the strongest odor around your engine.

Why do you have a "big electric pump" on it??????

He put a big pump on it ,and run 1/2inch line all way to front said it needed it

Ken, it would help a lot if you'd describe your whole fuel system, back to front and return, in as much detail as you can - connections, components, settings (regulator? carb floats), etc. If you've got a strong odor of raw gasoline for an extended period you've got a leak that's vaporizing fuel. Nothing wrong with the big pump and line, provided you're talking big flow volume with a capable pressure regulator, and not high pressure unless you're running fuel injection?

An open cup of gasoline sitting on the counter won't create the smell you're describing. It has to vaporize, like dripping into a big puddle or onto a hot/warm surface. You're looking for a leak, internal or external the way I see it.

Ken--refresh us on what the engine is, what your using for intake( carb/ efi ) and possibly just exactly what fuel pump you have plus how are you using this car?

I've went back and read thru many of your posts--------------I would suggest that you begin being a little more up front on exactly what you have and be curtious and answer some questions that have been asked of you plus stop starting a new subject every time------

For starters--------you can probably slove all your fuel issues by installing a mechanical pump on the BBC--------and removing the electric pump-its pretty obvious that you are most likely running too high of a fuel pressure that the needle/seats won't control resulting in engine flooding, washing down cylinders
etc------this often will result with raw gas getting into the hot exhaust system on shut down and will cause GASSY smell/ fumes for hours in an enclosed space or even nearby while outside-------

I also must mention that these conditions often result in a fire that grows into an unstoppable mess because the electric pump may not be wired with proper safety methods and the pump continues until tank is empty-------and it may be able to empty the tank before the fire department arrives

My car is a 68 chevelle ss with a 489 stroker 9.7to1 compression , it Dyno 649 hp an 591 tq , it's got aliumum AFR heads ,all callies bottom, it has a magna fuel electric fuel pump with 1/2 gas line front to back and a aero fuel pressure gage , the block was a 454 1991 4 bolt can't run manual fuel pump , it has a 950 quick fuel carb with 84 in front and 94 in back , timing is locked dn on 40 degrees that's were it made its most power at , iam having problems with fuel pressure I can set gage at 6 lbs drive it to town it might be on 0 but still be running ok or it might be on 10 and the float bowls fluctuate, took plugs out tonight and they were wet they are 3924 autolite, also can feel a little quiver miss when after it pretty hard , smells like raw gas in garage , I hope I have covered everything,

Originally Posted by Ken1960

I can set gage at 6 lbs drive it to town it might be on 0 but still be running ok or it might be on 10 and the float bowls fluctuate,

Ken, when you say you can "...set the gage" that infers that you have some type of fuel pressure regulator, and based on what you're saying I'd take a WAG and say it's either not compatible with your pump output pressure & volume flow, or it's just bad. I think I'd be shopping for a good quality fuel pressure regulator that holds your pressure more like 4 psig steady, regardless of your throttle position. Also, if your gauge us not a liquid filled unit replace it too. You need liquid filled to damp out the harmonics and give you a steady needle. Again, this is my WAG, reading between the lines of your post.

Originally Posted by Ken1960

iam having problems with fuel pressure I can set gage at 6 lbs drive it to town it might be on 0 but still be running ok or it might be on 10 and the float bowls fluctuate,

I have a Professional Products regulator on mine it did the same thing as yours (about 4 years old), bought their rebuild kit and it fixed it.

If your fuel pressure guage is near the carb or anywhere near the engine where heat will effect it-----it won't be consistant and/or accurate--------you will only rear pressure that the needle/seats hold closed and it will read less where they are passing fuel-----try setting the pressure down to 2 or 3 lbs and see if conditions show any improvement------also try shutting pump off and see if engine runs better as it clears up.

and 40 degrees timing in todays PC homofuelinjected day is crazy

Can you post some pics of pump, carb, fuel lines around carb, lower front of the block, tank fill neck, vents????????

Originally Posted by jerry clayton

If your fuel pressure guage is near the carb or anywhere near the engine where heat will effect it-----it won't be consistant and/or accurate--------you will only rear pressure that the needle/seats hold closed and it will read less where they are passing fuel...

I don't disagree, but the effects of ambient temperature, the temperature immediately around the gauge heating up the gauge internals, does affect the accuracy but won't affect the repeatability or consistency of the measurement if it's a good gauge. For every 18F that you increase the gauge temp (temperature of the bourdon tube in the gauge, not just the surroundings) above the calibration temperature you'll affect accuracy only about plus or minus 0.04%. If a gauge was calibrated at room temperature, say 70F, and the gauge is operating at 360F consistent ambient then the accuracy of the reading will be off by as much as 0.65% which means that a setting of 4 psig may be 3.97 to 4.026 psig, well within acceptable margins for carb fuel pressure measurements.

If the gauge shows a dip in pressure as the needle pulls off the seat, that is showing that the regulator is not responding quickly enough to maintain flow.

I'd still be looking at the regulator, especially based on 36 sedan's experience.

Your fuel smell could be heat soak.

After the engine shuts off, the carb rapidly heats up, without air flow to cool it. Then the gas boils in the bowls, the pressure forces the fuel out into the manifold where it evaporates and exits through the carb.

A quick check would be to shut the car down outside and let it get dead cold. Then push it in the garage and see if you get the gas smell. If no smell, then heat soak is possible.

Heat soak will indeed make your garage smell of gas! My 2 x 4's did exactly that until I put Edelbrock's 1/2" wood spacers under the carbs, makes it re-start when warmed up easier too.